Nasal continuous positive airway pressure device and system

ABSTRACT

An nCPAP device including a generator body defining first and second fluid flow circuits each including a tube and first and second nozzles. The tube defines a passageway forming an axial centerline. The first and second nozzles are associated with the tube and each defines an inlet and an outlet. The inlets are open to a fluid supply, whereas the outlets are open to the passageway. Each nozzle is adapted to emit a fluid jetstream from the outlet along a flow direction axis. The nozzles are arranged such that the flow direction axes are non-parallel relative to each other and relative to the axial centerline. This configuration readily induces vortex shedding during an expiratory phase, thus facilitating jet fluid flow disruption and reducing a patient&#39;s work of breathing.

BACKGROUND

The present invention generally relates to devices and methods forgenerating and delivering continuous positive airway pressure therapy topatients, such as infants. More particularly, the present inventionrelates to a variable flow, nasal continuous positive airway pressuredevice, system, and method with improved work of breathingcharacteristics.

Continuous positive airway pressure (CPAP) therapy has been employed formany years to treat patients experiencing respiratory difficultiesand/or insufficiencies. More recently, CPAP therapy has been advanced asbeing useful in assisting patients with under-developed lungs (inparticular, infants and especially premature infants or neonates), bypreventing lung collapse during exhalation and assisting lung expansionduring inhalation.

In general terms, CPAP therapy entails the continuous transmission ofpositive pressure into the lungs of a spontaneously breathing patientthroughout the respiratory cycle. CPAP can be delivered to the patientusing a variety of patient interface devices, for example anendotracheal tube. With infants, however, it is more desirable to employa less invasive patient interface device, in particular one thatinterfaces directly or indirectly with the nasal airways via thepatient's nares (e.g., mask or nasal prongs). Such systems are commonlyreferred to as nasal continuous positive airway pressure (nCPAP)systems.

In theory, the CPAP system should deliver a constant, stable pressure tothe patient's airways. With conventional, ventilator-based CPAP devices,a relative constant and continuous flow of gas (e.g., air, O₂, etc.) isdelivered into the patient's airways, with this airflow creating apressure within the patient's lungs via a restriction placed on outflowfrom the patient. Unfortunately, this continuous flow can have anadverse effect on the patient's respiratory synchrony. Moreparticularly, the patient is required to exhale against the incominggas, thus increasing the patient's work of breathing. Control valves canbe employed to better accommodate inspiratory and expiratory stages of apatient's breathing (e.g., controlling gas flow into the system and/oraltering an extent of restriction to outflow from the system). However,for many patients, especially infants, the ventilator approach is lessthan satisfactory as the patient's required work of breathing remainsquite high. That is to say, it is essentially impossible for a controlvalve system to accurately replicate the actual respiratory cyclesexperienced by the patient, such that the patient will consistently berequired to exhale against the high momentum, incoming gas, as well asagainst the resistance of the control valve(s). For an infant with underdeveloped lungs, even a slight increase in the required work ofbreathing may render the CPAP system in question impractical.

More recently, nCPAP systems have been developed that incorporate avariable flow concept in combination with separate channels forinspiratory and expiratory gas to and from the patient. When the patientinhales, the incoming gas takes the path of least resistance and isdirected to the patient's airways. Upon expiration, the gas again takesthe path of least resistance and goes out an exhalation or exhaust tube,thus reducing resistance during the expiratory phase. For example, theInfant Flow™ system, available from Viasys Healthcare, Inc., ofConshohocken, Pa., includes a variable flow CPAP generating device (or“CPAP generator”) that purportedly causes the direction of the suppliedgas to change with the infant's breathing patterns while maintaining aconstant pressure throughout the respiratory cycle. The Infant Flow CPAPgenerator forms two conduits (one for each of the patient's nares), andan exhaust tube. Gas is directed into each respective conduit via aninjector nozzle. The momentum of the gas jet acting over the area of theconduit creates a positive pressure inside the patient's lungs, inaccordance with known jet pump principles. To accommodate expiratoryflow from the patient, the generator relies upon what the manufacturer'sliterature characterizes as a “fluidic flip” effect. More particularly,the expiratory airflow from the patient applies a pressure onto theincoming flow (within the conduit) from the injector nozzle. It has beentheorized that due to the coanda effect, the expiratory airflow causesthe nozzle flow to deflect, thus triggering a fluidic flip of theairflow from the nozzle. As a result, fluid flow from the nozzle, aswell as the expiratory airflow, readily proceed to the exhaust tube,thus reducing the patient's required work of breathing. While highlypromising, current nCPAP products incorporating the “fluidic flip”approach may be less than optimal. For example, the injector nozzleairstream has a relatively high momentum that may not be easily overcomeby the patient's expiratory breathing, especially with infants.

In light of the above, a need exists for an improved nCPAP device,system, and method.

SUMMARY

Some aspects in accordance with principles of the present inventionrelate to a nasal continuous positive airway pressure (nCPAP) device foruse with an nCPAP system. The device includes a generator body defininga patient side and an exhaust side. The generator body forms at leastfirst and second fluid flow circuits. Each of the fluid flow circuitsincludes a tube and at least first and second nozzles. The tube definesa passageway forming an axial centerline. The passageway extends from aproximal end of the tube that is otherwise open to the patient side, toa distal end of the tube that is otherwise open to the exhaust side. Thefirst and second nozzles are associated with the tube and each define aninlet end and an outlet end. The inlet end of each of the nozzles isopen to a fluid supply, whereas the outlet end, respectively, is open tothe passageway. In this regard, each nozzle is adapted to emit a fluidjetstream from the outlet end along a corresponding flow direction axis.With this in mind, the first and second nozzles are arranged such thatthe corresponding flow direction axes are non-parallel relative to eachother and relative to the corresponding passageway axial centerline.With this configuration, the generator body includes two majorpassageways each delivering continuous positive pressure to a patient,with each passageway being supplied with fluid via at least two jetflow-inducing nozzles. In one embodiment, the nozzles are arrangedrelative to the corresponding tube/passageway such that thecorresponding flow direction axes, and thus the emitted fluidjetstreams, intersect or impinge upon each other at the axial centerlineof the corresponding passageway.

In one non-limiting embodiment, the generator body includes an exhaustport, a jet body, a manifold cover, and an interface plate. The exhaustport forms an exhaust conduit. The jet body forms or provides portionsof the fluid flow circuits, including each of the nozzles, distalportions of each of the tubes, and a chamber fluidly connected to thedistal portion of the tubes. The manifold cover is assembled between theexhaust port and the jet body. In this regard, the manifold cover formsa supply port. The interface plate forms proximal portions of the firstand second tubes and is assembled to the jet body such that the proximaltube portions are fluidly connected to a corresponding one of the distaltube portions so as to complete the first and second tubes. Upon finalassembly, the supply port is fluidly connected to each of the nozzles,and the chamber is fluidly connected to the exhaust conduit.

Other aspects of the present invention relate to a nasal continuouspositive airway pressure (nCPAP) system including a generator body, afluid supply source, and exhaust tubing. The generator body defines apatient side and an exhaust side, and further forms first and secondfluid flow circuits. Each of the fluid flow circuits includes a tubedefining a passageway, along with first and second nozzles fluidlyconnected to the corresponding passageway. In this regard, relative toeach fluid flow circuit, flow direction axes defined by the first andsecond nozzles are non-parallel relative to an axial centerline definedby the corresponding passageway as well as relative to each other. Thefluid supply source is fluidly connected to an inlet end of each of thenozzles, respectively. Finally, the exhaust tubing is fluidly connectedto a distal end of each of the passageways, respectively. With thisconfiguration, upon securement of the generator body to a patient'snares, the system is configured to establish a continuous positiveairway pressure in the patient by delivering fluid from the fluid supplysource to the nozzles. The nozzles, in turn, create a primary fluidjetstream within the corresponding passageway. With this in mind, thesystem is characterized by an inspiratory phase of operation, in whichthe primary fluid jetstreams continuously flow toward the patient'snares (capable of entraining gas flow to meet a patient's inspiratorydemand), and an expiratory phase of operation in which air exhaled fromthe patient's nares readily disrupts the fluid jetstreams, therebyreducing the resistance to exhalation flow such that the exhaled airreadily flows to the exhaust tubing.

Other aspects in accordance with principles of the present inventionrelate to a method for establishing and delivering continuous positiveairway pressure to a patient. The method includes fluidly connecting agenerator body to nares of the patient. In this regard, the generatorbody defines a patient side and an exhaust side, and forms first andsecond airflow circuits. Each of the airflow circuits includes a tubedefining a passageway having a proximal end open to the patient side anda distal end open to the exhaust side. Further, each passageway definesan axial centerline. Each fluid circuit further includes first andsecond nozzles each defining an inlet end and an outlet end, with theoutlet end being open to the corresponding passageway. Further, eachnozzle defines a flow direction axis, with the nozzles being arrangedsuch that relative to a respective airflow circuit, the flow directionaxes are non-parallel relative to each other and relative to thecorresponding passageway axial centerline. With this in mind, fluid isforced from a supply source to the inlet ends of each of the nozzles. Aprimary fluid jetstream is created within each of the passageways. Inparticular, the respective first and second nozzles each emit asecondary fluid jetstream into the corresponding passageway and directedtowards the patient's nares. The secondary fluid jetstreams impinge uponeach other within the corresponding passageway, and combine to form theprimary fluid jetstream. The momentum of the jetstreams is convertedinto pressure. During periods of patient inhalation, the primary fluidjetstreams continuously flow toward the patient's nares, entrainingsupplemental flow as necessary to meet inspiratory demands. Conversely,during periods of patient exhalation, exhaled air from the patientdisrupts the secondary fluid jetstreams so as to eliminate the primaryjetstreams, thus minimizing resistance to exhaled airflow. As a result,the exhaled air flows through the passageways to the exhaust side of thegenerator body. In one embodiment, the secondary fluid jetstreams arecharacterized as being low momentum jets. In another embodiment, themethod is characterized by, during periods of exhalation, the exhaledair from the patient disrupting the secondary jetstreams to generatestreamwise vortices that prevent flow separation in the exhalation flow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present invention and are incorporated in and are apart of this specification. Other embodiments of the present invention,and many of the intended advantages of the present invention, will bereadily appreciated as they become better understood by reference to thefollowing detailed description. The elements of the drawings are notnecessarily to scale relative to each other. Like reference numeralsdesignate corresponding similar parts.

FIG. 1 is a block diagram illustrating one embodiment of a nasalcontinuous positive airway pressure system including an nCPAP device inaccordance with principles of the present invention;

FIG. 2A is a perspective view of an embodiment of a generator bodyportion of the nCPAP device in accordance with principles of the presentinvention;

FIG. 2B is a longitudinal cross-sectional view of the generator body ofFIG. 2A;

FIG. 3 is an exploded view of one embodiment generator body inaccordance with principles of the present invention for use as thegenerator body of FIG. 2A;

FIG. 4A is a front view of a jet body component of the generator body ofFIG. 3;

FIG. 4B is a side cross-sectional view of the jet body of FIG. 4A;

FIG. 4C is a top cross-sectional view of the jet body of FIG. 4A;

FIG. 4D is a rear view of the jet body of FIG. 4A;

FIG. 5A is a front view of an interface plate component of the generatorbody of FIG. 3;

FIG. 5B is a top cross-sectional view of the interface plate of FIG. 5A;

FIG. 5C is a side cross-sectional view of the interface plate of FIG.5A;

FIG. 6A is a front perspective view of a manifold cover component of thegenerator body of FIG. 3;

FIG. 6B is a side cross-sectional view of the manifold cover of FIG. 6A;

FIG. 7A is a front view of an exhaust port component of the generatorbody of FIG. 3;

FIG. 7B is a side cross-sectional view of the exhaust port of FIG. 7A;

FIG. 7C is a rear perspective view of the exhaust port of FIG. 7A;

FIGS. 8A and 8B are cross-sectional views illustrating assembly of thegenerator body of FIG. 3;

FIG. 8C is a perspective view of an nCPAP device in accordance withprinciples of the present invention, including the generator body ofFIG. 3;

FIG. 9A is a perspective, exploded view of the generator body of FIG. 3in combination with one embodiment of a patient interface piece;

FIG. 9B is a bottom cross-sectional view of the patient interface pieceof FIG. 9A;

FIG. 9C is a bottom cross-sectional view of the combination generatorbody and patient interface piece of FIG. 9A upon final assembly;

FIG. 10A is a cross-sectional view of the nCPAP device of FIG. 8Cillustrating fluid flow during an inspiratory phase of operation;

FIGS. 10B and 10C are cross-sectional views of the nCPAP device of FIG.10A illustrating fluid flow during an expiratory phase of operation;

FIGS. 11A and 11B are photographs of a portion of an nCPAP device inaccordance with the present invention during an inspiratory phase ofoperation; and

FIGS. 12A and 12B are photographs of the nCPAP device of FIGS. 11A and11B during an expiratory phase of operation.

DETAILED DESCRIPTION

One embodiment of a nasal continuous positive airway pressure (nCPAP)system 20 incorporating an nCPAP device 22 in accordance with principlesof the present invention is shown in block form in FIG. 1. In generalterms, the system 20 is adapted to provide CPAP therapy to a patient 24,and includes the nCPAP device 22, a fluid supply 26, and a pressuremonitor 28. The nCPAP device 22 is described in greater detail below,and generally includes a generator body 30, a patient interface piece32, and exhaust tubing 34. The generator body 30 is fluidly connected toboth the patient interface piece 32 and the exhaust tubing 34, with thepatient interface piece 32 being adapted to establish fluidcommunication with the patient's 24 nasal airways. The fluid supplysource 26 provides the generator body 30 with a continuous flow of fluid(e.g., gas such as air and/or oxygen). The pressure monitor 28 is alsofluidly connected to the generator body 30 and samples or measurespressure therein. During use, the generator body 30 generates anddelivers a continuous positive airway pressure to the patient 24 via thepatient interface piece 32. As the patient 24 exhales, the exhaled airreadily flows through the patient interface piece 32/generator body 30,and is exhausted from the nCPAP device 22 via the exhaust tubing 34 asdescribed below. As used throughout the specification, directionalterminology such as “proximal” and “distal” are used with reference toan orientation of the component in question relative to the patient 24.Thus, “proximal” is closer to the patient 24 as compared to “distal”.

One embodiment of the generator body 30 in accordance with principles ofthe present invention is shown in FIG. 2A. The generator body 30 is, inone embodiment, comprised of several interrelated components thatcombine to form various features. These components are described ingreater detail below. Notably, the generator body 30 features can beaccomplished via configurations otherwise not including separatelyformed and subsequently assembled components. Thus, an initialexplanation of broader aspects of the generator body 30 is helpful tobetter appreciate a context of the components relative to the generatorbody 30 as a whole.

In general terms, the generator body 30 is configured to establish avariable flow CPAP via separate channels for inspiratory and expiratoryflow of fluid (e.g., gas) to and from the patient (not shown). Thus, thegenerator body 30 can be generally described as defining a patient side36 and an exhaust side 38. With these conventions in mind, and withadditional reference to FIG. 2B, the generator body 30 generally definesor forms first and second fluid flow circuits 40 a, 40 b (referencedgenerally in FIGS. 2A and 2B; only the first fluid flow circuit 40 a isshown in FIG. 2B). The fluid flow circuits 40 a, 40 b each include atube 42 a, 42 b defining a passageway 44 a, 44 b. The first tube 42a/passageway 44 a is shown more clearly in FIG. 2B. The tubes 42 a, 42 bare arranged in a juxtaposed fashion, extending from an open, proximalend 46 a, 46 b (i.e., adjacent the patient side 36) to an open, distalend (a distal end 48 a of the first tube 42 a being shown in FIG. 2B)and defining an axial centerline C (shown for the first fluid flowcircuit 40 a in FIG. 2B). A plurality of nozzles (hidden in FIG. 2A,referenced generally at 50 in FIG. 2B) are fluidly associated withrespective ones of the passageways 44 a, 44 b. For example, and as bestshown in FIG. 2B, the generator body 30 forms first and second nozzles50 a, 50 b that are fluidly connected to the passageway 44 a defined bythe first tube 42 a. Though not specifically shown, a similar nozzlearrangement is provided with respect to the passageway 44 b defined bythe second tube 42 b. Regardless, the nozzles 50 a, 50 b are oriented ina predetermined manner relative to the axial centerline C, as describedbelow.

While the first and second fluid circuits 40 a, 40 b are shown anddescribed as being identical, in alternative embodiments, the fluidcircuits 40 a, 40 b are not identical in terms of one or more of size,shape, orientation, etc. Similarly, while the fluid circuits 40 a, 40 bare each described as including two nozzles 50, one or both of the fluidcircuits 40 a, 40 b can include three or more of the nozzles 50. Evenfurther, in other embodiments more than two of the fluid circuits 40 a,40 b can be formed. Regardless, and with specific reference to FIG. 2B,each of the nozzles 50 a, 50 b extends from an inlet end 52 to an outletend 54, with the outlet end 54 having a reduced diameter as compared tothe inlet end 52. The inlet end 52 of each of the nozzles 50 a, 50 b isfluidly connected to a manifold 56. Finally, the generator body 30 formsa chamber 58 fluidly connecting the open, distal end (e.g., the distalend 48 a) of each of the passageways 44 a, 44 b (FIG. 2A) to an exhaustconduit 60.

With the above general structural features in mind, fluid flow into themanifold 56 is directed through the nozzles 50 that in turn convert thefluid flow into low momentum jetstreams directed into the correspondingtubes 44 a, 44 b. The so-generated jetstreams are described in greaterdetail below. Generally, however, a primary jetstream or jet pump isresultingly generated within the passageways 44 a, 44 b, generallydirected toward the patient side 36 (and thus the patient) and creatinga continuous positive airway pressure within the passageways 44 a, 44 b(e.g., the primary jetstream momentum is converted into pressure). Thus,during an inspiratory phase of operation, a continuous positive airwaypressure is delivered to the patient. To this end, the primary jetstreamis generated so as to enhance entertainment of supplemental gas whenrequired (e.g., when patient's inspiratory demand exceeds set flow ofthe primary jetstream). Conversely, during an expiratory phase ofoperation, exhaled air (from the patient) entering the passageways 44 a,44 b at the proximal end 46 a, 46 b, respectively, readily disrupts thejetstreams, effectively eliminating the primary jetstreams. Fluid flowfrom the nozzles 50 is then caused to fold backwards. As a result,resistance to flow of the exhaled air is minimized, effectivelyincreasing the hydraulic diameter of the flow path. Thus, the exhaledair and fluid flow from the nozzles 50 are directed through thepassageways 44 a, 44 b to the chamber 58/conduit 60.

With the above principles in mind, components of the generator body 30in accordance with one embodiment are shown in greater detail inexploded view of FIG. 3. The generator body 30 includes a jet body 70,an interface plate 72, a manifold cover 74, and an exhaust port 76. Ingeneral terms, the manifold cover 74 is disposed between the jet body 70and the exhaust port 76, and combines with the jet body 70 to form themanifold 56 (FIGS. 2A and 2B). The interface plate 72 is assembled tothe jet body 70, with the jet body 70/interface plate 72 combining todefine the tubes 42 a, 42 b/passageways 44 a, 44 b (FIG. 2B). Theinterface plate 72 is further configured to provide fluid connection tothe patient interface piece 32 (FIG. 1). Conversely, the exhaust port 76fluidly connects passageways formed by the jet body 70/interface plate72 to the exhaust tubing 34 (FIG. 1).

The jet body 70 is shown in greater detail in FIGS. 4A-4D. In oneembodiment, the jet body 70 includes a housing 90 forming or surroundingfirst and second distal tubular members 92 a, 92 b as well as thechamber 58. As described in greater detail below, the distal tubularmembers 92 a, 92 b define distal segments of the tubes 42 a, 42 b (FIG.2A) upon final assembly with the interface plate 72 (FIG. 3). Further,the housing 90 defines or surrounds the nozzles 50 (referenced generallyin FIGS. 4A and 4B). Finally, in one preferred embodiment, the jet body70 further includes an intermediate wall 94, a pressure monitoring port96, and mounting features 98 (best shown in FIG. 4A). As describedbelow, the intermediate wall 94 fluidly isolates the chamber 58 fromportions of the jet body 70 proximal thereof. The pressure monitoringport 96 is located to tap or sample air pressure within the generatorbody 30 (FIG. 2A). Finally, the mounting features 98 provide a means forsecuring the jet body 70, and thus the assembled generator body 30, to apatient.

Commensurate with the above description and with specific reference toFIGS. 4B and 4C, the housing 90 can be described as defining a proximalsegment 100, an intermediate segment 102, and a distal segment 104. Thesegments 100-104 are continuous, and each define certain features of thejet body 70, including promoting assembly to other components.

For example, the proximal segment 100 forms an opening 106 sized toreceive and maintain the interface plate 72 (FIG. 3) as well as aportion of a patient interface piece (not shown). In one embodiment, theproximal segment 100, and thus the opening 106, is generally oval-likein a front planar view (FIG. 4A), although other shapes are alsoacceptable. Further, a shape of the opening 106 can also have certain,non-symmetrical attributes that promote assembly of the patientinterface piece at a desired orientation relative to the jet body 70, asdescribed below.

The intermediate segment 102 forms or maintains the distal tubularmembers 92 a, 92 b, and the nozzles 50 (as best shown in FIG. 4B). Inone embodiment, the nozzles 50 are molded in (or formed by) theintermediate segment 102 (and thus the jet body 70). As compared to aCPAP generator configuration in which the jet-producing nozzle is formedapart from, and subsequently assembled to, a primary conduit housing,the integrally molded nozzles 50 are less likely to leak during use(that in turn might otherwise expose the patient to higher-than orlower-than expected pressure conditions). Alternatively, however, thenozzles 50 can be separately formed. In addition, the intermediatesegment 102 defines an interior surface 107.

The distal segment 104 defines the chamber 58, with the intermediate anddistal segments 102, 104 being separated by the intermediate wall 94. Inaddition, an exterior of the intermediate and distal segments 102, 104is configured to be received by, and for attachment to, the manifoldcover 74 (FIG. 3) as described below.

Relative to the above explanation of the housing 90, the distal tubularmembers 92 a, 92 b are, in one embodiment, identical, such that thefollowing description of the first distal tubular member 92 a along withits relationship to the corresponding nozzles 50 applies equally to thesecond distal tubular member 92 b and the corresponding nozzles 50. Withthis in mind, the distal tubular member 92 a extends from a distal side108 formed in the intermediate wall 94 to a proximal side 110 that isotherwise laterally spaced from the interior surface 107 of the housingintermediate segment 102. A majority of the distal tubular member 92 ais substantially uniform in diameter, expanding slighting at the distalside 108 (that is otherwise fluidly open to the chamber 58). Thisexpansion in diameter promotes laminar fluid flow from the distaltubular member 92 a into the chamber 58. By way of example, but in noway limiting, the distal tubular member 92 a has an inner diameter onthe order of 0.194 inch, with each of the nozzles 50 a, 50 b (FIG. 4C)projecting into this so-defined diameter.

Further, the distal tubular member 92 a defines the axial centerline C(it being understood that the axial centerline C shown in FIG. 4C isalso the axial centerline C (FIG. 2B) of the passageway 42 a (FIG. 2B)upon final assembly with the interface plate 72 (FIG. 3)). As shown, thenozzles 50 a, 50 b are fluidly open to the distal tubular member 92 a atthe proximal side 110 and are arranged in a non-parallel fashionrelative to the axial centerline C, as well as to each other. Moreparticularly, the nozzles 50 a, 50 b are formed at circumferentiallyopposite sides of the tubular portion 92 a such that the respectiveoutlet ends 54 each project into the distal tubular member 92 a. Thenozzles 50 a, 50 b each define a flow direction axis D₁, D₂. The flowdirection axes D₁, D₂ corresponds with the central axis defined by therespective nozzles 50 a, 50 b, and define the direction in which fluidexits from the respective outlet end 54 thereof. With this in mind, inone embodiment, the nozzles 50 a, 50 b are arranged such that the flowdirection axes D₁, D₂ intersect or impinge upon each other approximatelyat the axial centerline C. That is to say, the nozzle 50 a, 50 b aresymmetrically arranged about the axial centerline C. To this end, and inone embodiment, the nozzles 50 a, 50 b are angularly oriented relativeto the axial centerline C such that the flow direction axes D₁, D₂combine to define an included angle Θ in the range of 40°-80°,preferably 50°-70°, more preferably approximately 60° (±1°). Inaddition, each of the nozzles 50 a, 50 b are configured to generatejetstream fluid flow via a constricted fluid flow path from the inletend 52 to the outlet end 54. For example, in one embodiment, the inletend 52 has a diameter of approximately 0.069 inch, whereas an outlet end54 has a diameter of approximately 0.0245 inch (it being understood thata wide variety of other dimensions are equally acceptable). Regardless,fluid jetstreams produced by the nozzles 50 a, 50 b impinge upon oneanother and combine approximately at the axial centerline C. Inalternative embodiments, three or more of the nozzles 50 can beassociated with the distal tubular member 92 a, disposed at variouscircumferential locations about the distal tubular member 92 a; withmany of these alternative embodiments, however, the corresponding flowdirections axes established by each of the multiplicity of nozzles 50all impinge upon one another at approximately the axial centerline C. Inother alternative embodiments, the nozzles 50 are located and/ororiented in an offset relationship such that the corresponding flowdirection axes D₁, D₂ intersect at a point away from the axialcenterline C. This configuration will induce swirling during anexpiratory mode of operation, as described below.

In addition to defining or surrounding the outlet ends 54 of the nozzles50, the housing intermediate segment 102 also forms the inlet ends 52thereof such that the inlet ends 52 are open to an exterior of thehousing 90. For example, in one embodiment, an exterior of theintermediate segment 102 includes a rear surface 114 and a ledge 116.The rear surface 114 extends in an angular fashion (tapering intransverse cross-sectional area) from the ledge 116 to the distalsegment 104. As shown in FIG. 4D, the inlet end 52 of each of thenozzles 50 extends through, and is fluidly open relative to, the rearsurface 114, with the ledge 116 providing a surface for assembly of themanifold cover 74 (FIG. 3). Thus, the rear surface 114 completes themanifold 56 (FIG. 2B) upon final assembly of the manifold cover 74 tothe jet body 70 as described below.

With the above description of the housing 90 in mind, in one embodimentand as best shown in FIG. 4C, the pressure monitoring port 96 extendsfrom the housing 90 and forms an aperture 118 (shown with dashed lines)extending through the intermediate segment 102. The aperture 118 is opento an interior of the housing 90 proximal the intermediate wall 94 (FIG.4B), and in particular to a volumetric spacing 119 (referencedgenerally) between the distal tubular members 92 a, 92 b and theinterior surface 107 of the housing intermediate segment 102. Asdescribed in greater detail below, this location, in conjunction withfeatures of the interface plate 72 (FIG. 3), facilitates tapping ormeasurement of pressure within the jet body 70/generator body 30 (FIG.2A).

Finally, and returning to FIG. 4A, the mounting features 98 include, inone embodiment, a pair of flanges 120 a, 120 b extending in an opposingfashion from the housing proximal segment 100, each terminating in aclip 122 a, 122 b, respectively. Each clip 122 a, 122 b is spaced fromthe housing 90 to establish a gap 124 a, 124 b. The gaps 124 a, 124 bare sized to slidably receive a strap (not shown) otherwise used tosecure the generator body 30 (FIG. 2A) to a patient. The clips 122 a,122 b provide a surface for frictionally engaging the strap.Alternatively, the mounting features 98 can assume a variety of otherforms, and in some embodiments are eliminated.

Returning to FIG. 3, and with additional reference to FIGS. 5A-5C in oneembodiment, the interface plate 72 includes a frame 140, first andsecond proximal tubular members 142 a, 142 b, and first and secondconnection bodies 144 a, 144 b. In general terms, the connection bodies144 a, 144 b partially extend between the respective proximal tubularmembers 142 a, 142 b and the frame 140 so as to laterally space theproximal tubular members 142 a, 142 b from the frame 140.

The frame 140 is sized to nest within the opening 106 (FIG. 4A) of thejet body 70. Thus, in one embodiment, the frame 140 has a generallyoval-like shape (best shown in FIG. 5A), terminating in a relativelyflat rear surface 146 (FIGS. 5B and 5C) adapted for a sealing fit orassembly (e.g., welding) to the jet body housing 90 (FIG. 4A).Alternatively, the frame 140 can assume a variety of other forms.

In one embodiment, the proximal tubular members 142 a, 142 b arejuxtaposed and identically formed, such that the following descriptionof the first proximal tubular member 142 a applies equally to the secondproximal tubular member 142 b. With this in mind and with specificreference to FIGS. 5B and 5C, the proximal tubular member 142 a forms apassage 150 and is defined by a distal region 152, an intermediateregion 154, and a proximal region 156. The proximal region 156terminates at the proximal end 46 a (otherwise corresponding or definingthe proximal end 46 a of the tube 42 a (FIG. 2A) upon final assembly).Conversely, the distal region 152 is sized and shaped for assembly overa corresponding one of the distal tubular members 92 a, 92 b (FIG. 4B)of the jet body 70. Thus, an inner diameter of the distal region 152 isgreater than an outer diameter of the corresponding distal tubularmember 92 a or 92 b. Notably, in one embodiment, the distal region 152extends distally beyond the rear surface 146 of the frame 140 forestablishing a pressure chamber (not shown) upon final assembly to thejet body 70 as described below.

The intermediate region 154 extends from, and has a reduced innerdiameter as compared to that of, the distal portion 152, and in oneembodiment includes a first portion 158 and a second portion 160. Thesecond portion 160 tapers in diameter from the first portion 158 to theproximal region 156. More particularly, an inner diameter of the firstportion 158 corresponds with a diameter of the corresponding distaltubular member 92 a (FIG. 4C), and is greater than an inner diameter ofthe proximal region 156. As described in greater detail below, thisenlarged area accommodates and promotes disruption of jetstream(s)during use. By way of example, but in no way limiting, an inner diameterof the first portion 158 is on the order of 0.194 inch, whereas an innerdiameter of the proximal region 156 is on the order of 0.142 inch.Alternatively, a wide variety of other dimensions are equallyacceptable, so long as at least a portion of the intermediate region 154(i.e., the first portion 158) has an inner diameter greater than that ofthe proximal region 156. Along these same lines, a longitudinal lengthof the first portion 158 corresponds with an angular orientation andtraverse offset distance between the nozzles 50 a, 50 b (FIG. 4C)otherwise associated with the distal tubular member 92 a to which theproximal tubular member 142 a is assembled. More particularly, the firstportion 158 is sized such that upon final assembly, the jetstreamsgenerated by the nozzles 50 impinge upon each other proximate or withinthe second portion 160 and/or the proximal region 156 (i.e., region withreduced diameter) to ensure formation of a primary jetstream or jetpump. In one embodiment, but in no way limiting, the first portion 158has a longitudinal length of approximately 0.134 inch.

Finally, the proximal region 156 extends proximally outwardly relativeto the frame 140 and defines a surface for receiving a correspondingportion of the patient interface piece 32 (FIG. 1). In one embodiment,and as best shown in FIGS. 3 and 5B, a radial slot 162 is formed alongan interior side 164 of the proximal tubular member 142 a (i.e., theside facing the opposing proximal tubular member 142 b), extending fromthe proximal end 46 a. The radial slot 162 is sized in accordance withthe patient interface piece 32 (FIG. 1) and, as described below,provides a region from which pressure otherwise present within theproximal tubular member 142 a can be tapped or sampled. In oneembodiment, the radial slot 162 has a longitudinal length on the orderof 0.05-0.5 inch, although other dimensions are equally acceptable. Inother embodiments, dimension(s) of the slot 162 are correlated with aninner diameter of the tubular member 142 a at the proximal end 64thereof. It has been surprisingly discovered that pressure beingdelivered to a patient can be sampled with high accuracy but withminimal or no occurrences of back pressure generation by forming theradial slot 162 to have a length that is no more than 85% of the innerdiameter of the tubular member 142 a at the proximal end 64 and/or awidth that is no less than 25% of the inner diameter of the tubularmember 142 a at the proximal end 64. Regardless, the second proximaltubular member 142 b similarly forms the radial slot 162 (along a sidefacing the first proximal tubular member 142 a).

Finally, the connector bodies 144 a, 144 b extend from a portion of acircumference of the corresponding proximal tubular member 142 a, 142 b.In this regard, and as best shown in FIG. 5A, first and second pressuretaps or cutouts 166, 168 are defined between the connector bodies 144 a,144 b. The cutouts 166, 168 establish a fluid connection between theradial slots 162 and a rear face 170 (referenced generally in FIG. 5B)of the interface plate 72. As described below, the cutouts 166, 168facilitate tapping or sampling of pressure within the generator body 30(FIG. 2A) upon final assembly.

With reference to FIGS. 6A and 6B, in one embodiment the manifold cover74 includes a side wall 180, a partition 182, and a supply port 184. Theside wall 180 forms a continuous, tubular body that extends from a frontside 186 to a rear side 188. In this regard, the side wall 180 is sizedfor assembly about a portion of the jet body housing 90 (FIG. 4A) andthus has, in one embodiment, an oval-like shape in transversecross-section.

The partition 182 extends radially inwardly from the rear side 188 ofthe side wall 180, terminating at an edge 190 that defines an opening192. The opening 192 is fluidly open to an interior of the tubular sidewall 180 and is sized to receive the jet body housing distal segment 104(FIG. 4C). Thus, in one embodiment, the edge 190/opening 192 defines anoval-like shape.

Finally, and with specific reference to FIG. 6B, the supply port 184extends outwardly from the side wall 180, forming an aperture 194through a thickness thereof. The support port 184 is configured forassembly to, and fluid connection with, tubing (not shown), such astubing extending from a fluid supply source. With this construction,then, the supply port 184 provides fluid connection between a fluidsupply source an interior of the tubular side wall 180. As describedbelow, the supply port 184 thus facilitates delivery of fluid flow tothe generator body 30 (FIG. 2A).

The exhaust port 76 is shown in greater detail in FIGS. 7A-7C. Theexhaust 76 includes a conduit body 200 forming the conduit 60 previouslydescribed. In one embodiment, the conduit body 200 includes a firstsegment 202 and a second segment 204. The first segment 202 extends in agenerally longitudinal fashion from a front face 206 otherwiseincluding, in one embodiment, a partial rim 208. The partial rim 208 isbest shown in FIG. 7A and provides an enlarged surface that facilitatesassembly to the manifold cover partition 182 (FIG. 6A), such as viawelds. Regardless, the front face 206 is sized and shaped to receive thejet body housing distal segment 104 (FIG. 4A) to establish a fluidconnection between the chamber 58 (FIG. 4A) and the conduit 60.

The second segment 204 extends from the first segment 202 opposite thefront face 206, defining a bend in the range of 70°-110°, for exampleapproximately 90° in one embodiment. With this one construction, theexhaust port 76 promotes extension of associated exhaust tubing (notshown) in a desired direction away from the exhaust port 76, and thusrelative to the generator body 30 (FIG. 2A). To this end, in oneembodiment, the second segment 204 forms a circumferential barb 210adjacent a trailing face 212 thereof. The barb 210 is configured tofacilitate securement of the exhaust tubing to the exhaust port 76 in amanner that allows the exhaust tubing to be rotated about the barb 210.Alternatively, the exhaust port 76 can incorporate various otherstructures that promote securement of the exhaust tubing, such that thecircumferential barb 210 can be eliminated. Along these same lines andwith particular reference to FIG. 7C, in one embodiment, the secondsegment 204 forms a groove 214 along a rear side 216 thereof. The groove214 facilitates release of excess pressure from within the exhaust port76/exhaust tubing during use. Alternatively, the groove 214 can beeliminated. While the first and second segments 202, 204 have beenillustrated as being rigidly connected, in alternative embodiments theexhaust port 76 is configured such that the second segment 204 isrotatably coupled to the first segment 202. With this configuration, auser can swivel the second segment 204 (and thus the exhaust tubingattached thereto) relative to the first segment 202 (and thus aremainder of the generator body 30) to a desired spatial location.

Assembly of the generator body 30 in accordance with principles of thepresent invention can be described with reference to FIGS. 8A and 8B. Inthis regard, while the components 70-76 are described as being assembledin a particular order, this is in no way limiting. With specificreference to FIG. 8A, the manifold cover 74 is assembled to the jet body70. More particularly, the distal segment 104 of the housing 90 of thejet body 70 is received within, and passes through, the opening 192defined by the partition 182 of the manifold cover 74. The front side186 of the manifold cover side wall 180 abuts against the ledge 116 ofthe jet body housing 90 such that the rear surface 114 of the jet bodyhousing 90, and thus the inlet ends 52 of the nozzles 50, are within theinterior region defined by the manifold cover side wall 180. Themanifold cover 74 is then affixed to the jet body 70, such as byultrasonically welding the front side 186 of the manifold cover sidewall 180 to the ledge 116 of the jet body housing 190. Upon finalassembly, the jet body housing 90 and the manifold cover side wall 180combine to define the manifold 56. More particularly, assembly of themanifold cover 76 to the jet body 70 establishes a fluid seal about themanifold 56, thus establishing a fluid connection between the supplyport 184 and the inlet end 52 of each of the nozzles 50. That is to say,the manifold cover 74 extends about an entirety of the distal segment104 of the jet body housing 90, such that each of the nozzles 50 arefluidly connected to the single manifold 56 that in turn is fluidlyconnected to the supply port 184.

The exhaust port 76 is then assembled over the distal segment 104 of thejet body housing 90 such that the conduit 60 is fluidly connected to thechamber 58. In one embodiment, the front face 206 of the exhaust portconduit body 200 is abutted against, and affixed to (e.g., welded), themanifold cover partition 182 and/or an exterior of the jet body distalsegment 104, thus establishing a fluid-tight seal.

With reference to FIG. 8B, the interface plate 72 is assembled to thejet body 70. More particularly, the interface plate frame 140 nestswithin the opening 106 of the housing proximal segment 100, with theproximal tubular members 142 a, 142 b of the interface plate 72 beingassembled to, and fluidly connected with, a respective one of the distaltubular members 92 a, 92 b of the jet body 70. Thus, upon final assemblyof the interface plate 72 to the jet body 70, the first proximal anddistal tubular members 142 a, 92 a combine to define the first tube 42a, and the second proximal and distal tubular members 142 b, 92 bcombine to define the second tube 42 b. In this regard, a fluid-tightseal (e.g., no fluid leakage at 3 psi) is established between thecorresponding tubular members 142 a/92 a and 142 b/92 b, such as viawelding of the interface plate 72 to the jet body 70. Regardless, eachof the so-constructed tubes 42 a, 42 b forms the correspondingpassageways 44 a, 44 b that are both fluidly connected to the chamber 58that in turn is fluidly connected to the conduit 60. Further, at leasttwo of the nozzles 50 (referenced generally) project within, and arefluidly connected to, a corresponding one of the passageways 44 a, 44 b,with the flow direction axes D (FIG. 4C) defined by the correspondingnozzles 50 intersecting or impinging upon one another approximately at,in one embodiment, the axial centerline C (FIG. 4C) of the passageway 44a or 44 b. Once again, the intermediate and proximal regions 154, 156 ofthe proximal tubular portions 142 a and 142 b form the resultant tube 42a or 42 b to have a larger inner diameter proximate the correspondingnozzle outlet ends 54 (i.e., along the first portion 158 (FIG. 4C)) ascompared to an inner diameter further downstream of the outlet ends 54(i.e., along the second portion 160 and the proximal region 156). By wayof reference, this increased diameter (and thus increased volume) isreflected in FIG. 8B as a relief zone 220 within each of the tubes 42 a,42 b.

Further, a spacing or pressure chamber 222 (referenced generally) isestablished between the jet body housing 90, the interface plate frame140, and exteriors of each of the proximal and distal tubular members142/92. The pressure chamber 222 is fluidly open at the cutouts 166, 168(hidden in FIG. 8B, but shown in FIG. 5A), and is fluidly connected tothe pressure monitoring port 96 (FIG. 4C). As described below, pressurewithin the generator body 30 adjacent the patient side 36 thereof istransmitted to the pressure chamber 222. The pressure chamber 222provides a means for venting pressure from the pressure taps or cutouts166, 168 (FIG. 5A) to the pressure monitoring port 96 for measuring thepressure within the generator body 30. As clarified below, the radialslots 162 define the locations from which pressure in the tube 42 a, 42b is sampled. Notably, because the radial slots 162 are located at theproximal end of the respective tubes 42 a, 42 b (and thus as close aspossible to the patient interface piece (not shown)), and furtherbecause the cutouts 166, 168 are in close proximity to the radial slots162 (e.g., on the order of 0.2 inch in one embodiment), a more accurateevaluation of pressure actually being delivered to the patient can bemade as compared to conventional nCPAP generator configurations.

In one embodiment, each of the generator body components 70-76 aremolded from a similar plastic material amenable to subsequent assemblyvia welding. For example, in one embodiment, each of the generator bodycomponents 70-76 are molded polycarbonate, although other plasticmaterials such as acrylic resins or acrylic copolymer resins, otherthermoplastic materials, etc., are also acceptable. Along these samelines, affixment of the components 70-76 to one another is characterizedby a fluid-tight seal in which leakage does not occur at pressures of 3psi. For example, welding (e.g., ultrasonic welding), adhesives, etc.,can be employed. Alternatively, two or more of the components 70-76 canbe integrally formed; for example, in one alternative embodiment, thegenerator body 30 can be molded or formed as a single, integral piece.It has been surprisingly found, however, that by forming the components70-76 separately from one another, tight tolerances on the primaryfeatures of the generator body 30 as a collective whole can be achievedwhile minimizing an overall size thereof. Further, in the one embodimentdescribed above, the components 70-76 are assembled in a stacked manner.All interface planes between adjacent components are essentiallyperpendicular to the direction of fluid flow toward the patient duringuse. Thus, any leaks that may occur between adjacent components 70-76are not open to the patient fluid flow, but instead flow to an exteriorof the generator body 30. This, in turn, prevents occurrences of highpressure leaks to the patient.

The assembled generator body 30 can then be provided with additionalcomponents in forming the nCPAP device 22 as shown in FIG. 8C. Forexample, a fluid supply tube 230 is fluidly connected at one end to thesupply port 184 and at an opposite end (not shown) to the fluid supply(not shown), such as a pressurized source of gas (e.g., air, oxygen,etc.). Similarly, vent tubing 232 is fluidly connected at one end to thepressure monitoring port 96 and at an opposite end (not shown) to apressure monitoring device (not shown). As previously mentioned, thepressure monitoring port 96 is open to fluid pressure within thegenerator body 30 such that the pressure monitoring device can determinethe level of pressure being delivered to the patient via the vent tubing232. Finally, the exhaust tubing 34 is assembled over, and fluidlyconnected to, the exhaust port conduit body 200. In one embodiment, thecircumferential barb 210 (FIG. 7A) provides longitudinally lockedsecurement of the exhaust tubing 34 to the exhaust port 76. In oneembodiment, the exhaust tubing 34 has a corrugated or accordion-likeconfiguration (e.g., corrugated, expandable/collapsible tubing), suchthat the exhaust tubing 34 can be readily oriented (e.g., bent) in adesired manner without effectuating a “pinch” in the exhaust tubing 34.In a further embodiment, the exhaust tubing 34 defines a primarycorrugated segment 234, a relief segment 236, and a leading end 238 asshown in FIG. 8C. The leading end 238 is configured for placement over,and securement to, the exhaust port 76 and thus is free of corrugations.The primary corrugated segment 234 extends along a majority of thetubing 34, and is structurally formed to expand or contract as desiredand dictated by the user, maintaining the expanded or contracted length.Conversely, while the relief segment 236 includes inwardly and outwardlyextending wall portions for easy expansion and contraction, it is of areduced wall thickness and is highly flexible (as compared to thecorrugated segment 234). This promotes an ability of a user to rotatethe exhaust tubing 34 relative to the exhaust port 76, yet the exhausttubing 34 remains longitudinally locked to the exhaust port 76.Alternatively, the exhaust tubing 34 (as well as the fluid supply tube230 and the vent tubing 232) can assume a variety of other forms. Forexample, the exhaust tubing 34 one or all of the tubing 34, 230, and/or232 can be formed of a rigid yet malleable material that can berepeatedly bent to a desired shape by a user, and independently maintainthe bent shape. As a point of reference, a length of each of the tubing34, 230, and 232 is attenuated in the view of FIG. 8C for ease ofillustration.

Prior to use of the nCPAP system 20 (FIG. 1), the patient interfacepiece 32 is assembled to the nCPAP device 22, and in particular thegenerator body 30, as shown in FIGS. 9A and 9B. The patient interfacepiece 32 can assume a variety of forms suitable for establishing fluidconnection to a patient's nasal airways (not shown). Thus, the patientinterface piece 32 can include an opposing pair of nasal prongs asshown. Alternatively, the patient interface piece 32 can be a maskotherwise establishing a singular fluid connection of the generator body30 to both of the patient's nasal airways. Regardless, in oneembodiment, the patient interface piece 32 includes a base 240 formed ofa resilient, compliant material and is configured to interact withcertain features of the generator body 30 as described below.

For example, in one embodiment the base 240 forms a pair of lumens 242a, 242 b extending through a thickness of the base 240, as well as achannel 244 extending between the lumens 242 a, 242 b. The channel 244and the lumens 242 a, 242 b are open relative to a distal face 246 ofthe base 240, with the channel 244 having a longitudinal lengthcorresponding with that of the radial slot 162 associated with each ofthe tubes 42 a, 42 b of the generator body 30. With this in mind,assembly of the patient interface piece 32 to the generator body 30includes mounting respective ones of the tubes 42 a, 42 b within arespective one of the lumens 242 a, 242 b. The base 240 is furtherlodged within the proximal segment 100 of the jet body housing 90 suchthat the base 240 is frictionally secured between the jet body housing90 and the tubes 42 a, 42 b.

In this regard, in one embodiment, a shape of the base 240 correspondswith a shape of the proximal segment 100 of the jet body housing 90. Inone preferred embodiment, the corresponding shapes are non-symmetricalto ensure a desired orientation of the patient interface piece 32relative to the generator body 30. For example, in one embodiment, thebase 240 and the proximal segment 100 of the jet body housing 90 includea pair of arcuate or generally curved corners 250, and a pair ofrelatively distinct or “sharp” corners 252 as shown in FIG. 9A (i.e.,the curved corners 250 have a larger radius of curvature as compared tothe sharp corners 252). With this configuration, the patient interfacepiece 32 cannot be accidentally assembled to the generator body 30 in anorientation opposite that shown in FIG. 9A. Alternatively, the patientinterface 32 can assume a variety of other forms that may or may includea non-symmetrically shaped base 240.

Regardless, in one embodiment, the patient interface piece 32 isconfigured to maintain a desired fluid connection between the proximalsegment 100 of the jet body housing 90 and the pressure monitoring port96. In particular and with reference to FIG. 9C, assembly of the base240 to the tubes 42 a, 42 b of the generator body 30 is such that thechannel 244 is open relative to the radial slot 162 defined by each ofthe tubes 42 a, 42 b. Thus, fluid flow within the passageways 44 a, 44 bcan flow outwardly therefrom via the radial slots 162 and the channel244. Further, fluid flow from the channel 244 is permitted to flow toand through the pressure taps or cutouts 166, 168 (it being understoodthat only the cutout 168 exists in the sectional view of FIG. 9C; thecutout 166 is illustrated in FIG. 5A) defined by the interface plate 72.The cutouts 166, 168, in turn, are fluidly open to the pressure chamber222 defined between the interface plate 72 and the proximal segment 100of the jet body housing 90. Thus, a pressure monitoring fluid circuit isestablished by a fluid connection of the pressure monitoring port 96(FIG. 9A) and the passageways 44 a, 44 b via the radial slots 162, thechannel 244, the cutouts 166, 168, and the pressure chamber 222. To thisend, by locating, in one embodiment, the radial slots 162 along aninterior side of the respective tube 42 a, 42 b and in highly closeproximity to the lumens 242 a, 242 b that otherwise are in direct fluidcommunication with the patient's nares, the pressure monitoring circuitis able to detect a pressure nearly identical to that actually beingseen by the patient (within 0.2-0.3 cm of actual pressure delivered topatient).

Notably, the nCPAP device 22, and in particular the generator body 30,in accordance with principles of the present invention is useful with awide variety of other patient interface piece configurations that may ormay not incorporate some or all of the features described above withrespect to the patient interface piece 32. Thus, the patient interfacepiece 32 is in no way limiting.

Operation of the nCPAP device 22, and in particular the generator body30, as part of the nCPAP system 20 (FIG. 1) is described with initialreference to FIG. 10A. For ease of illustration, the nCPAP device 22 isshown without the patient interface piece 32 (FIG. 9A). With this inmind, the nCPAP device 22 is secured to a patient (not shown). While thenCPAP device 22 of the present invention is useful with a wide varietyof patients, the nCPAP device 22 is highly appropriate for providingCPAP therapy to infants or neonates. Regardless, the nCPAP device 22 ismounted to the patient by securing a strap (not shown) about thepatient's head, and then securing the strap to the mounting features 98provided by the generator body 30. For example, the strap(s) is securedto the generator body 30 by nesting the strap(s) within the gaps 124 a,124 b (one of which is shown in FIG. 10A), with a positioning of thegenerator body 30 relative to the strap(s) being maintained by the clip122 a, 122 b (one of which is shown in FIG. 10A).

Once secured to the patient, fluid (e.g., air, oxygen, etc.) is suppliedto the generator body 30 via the supply tube 230. More particularly,fluid is forced into the supply port 184 that in turn directs the fluidflow into the manifold 56. The manifold 56 provides a fluid connectionto the inlet end 52 of each of the nozzles 50 (designated generally;shown in FIG. 10A as the nozzles 50 a, 50 b), such that the suppliedfluid is forced into the nozzles 50. The nozzles 50, in turn, eachcreate a low momentum secondary jetstream fluid flow within thecorresponding passageway 44 a, 44 b (FIG. 2A). For example, FIG. 10Aillustrates the passageway 44 a defined by the tube 42 a, along with thenozzles 50 a, 50 b. The first nozzle 50 a creates a first, low momentum,secondary jetstream S₁ within the passageway 44 a. Similarly, the secondnozzle 50 b creates a second, low momentum, secondary jetstream S₂within the passageway 44 a. As used throughout the specification, thephrase “low momentum” is in comparison to the nozzle-induced, jetstreammomentum found with conventional nCPAP generators otherwiseincorporating a single nozzle. By way of example, to deliver a CPAP of 5cm of water, a single nozzle will be required to generate a jetstreammomentum of 10 millinewton over a 0.2 inch diameter conduit. Incontrast, with the generator body 30 embodiment shown, the CPAP of 5 cmof water is created with each of the nozzles 50 a, 50 b generating ajetstream momentum of 5 millinewton.

With additional reference to FIG. 4C, the first secondary jetstream S₁projects from the first nozzle 50 a in the flow direction axis D₁,whereas the second secondary jetstream S₂ projects in the flow directionaxis D₂. Due to the previously described orientation of the nozzles 50a, 50 b relative to the axial centerline C of the passageway 44 a, thesecondary jetstreams S₁, S₂ intersect and impinge upon one anotherapproximately at the axial centerline C, creating a primary jetstream orjet pump P. Effectively, then, the low momentum secondary jetstreams S₁,S₂ combine with one another to establish or generate a stable, highermomentum jet pump flowing in a direction toward the patient (i.e., thepatient side 36 of the generator body 30). The jet pump thus serves as alow momentum positive airway pressure source for the patient (i.e.,momentum of the jet pump is converted into pressure).

During periods of time in which the patient is inhaling (“inspiratoryphase”), the primary jetstream P readily flows toward the patient'snasal airways via the passageway 44 a (and 44 b). Because the interfacepoint between the secondary jetstreams S₁, S₂ is at or about the reduceddiameter proximal region 156 of the passageway 44 a, any vortices (i.e.,swirling fluid flow) produced by the impinging jetstreams S₁, S₂ arenominal and readily constrained within the passageway 44 a. Thus, duringthe inspiratory phase, a continuous positive airway pressure isgenerated within, and delivered to the patient by, the passageways 44 a,44 b. Further, by approximately centering the primary jetstream P withinthe respective passageway 44 a, 44 b, and providing the reduced diameterproximal region 156, a venturi effect is created that enhancesentrainment of supplemental gas into the airflow toward the patient soas to meet the patient's inspiratory demands. In other embodiments, thegenerator body 30 is configured such that a diameter of at least one ofthe nozzles 50 a, 50 b can be varied. For example, a mandrel or pin canbe slidably disposed within the nozzle 50 a or 50 b, and assembledthereto such that a user can move the pin toward or away from the outletend 54, thus changing an effective diameter of the outlet end 54. This,in turn, allows the user to change the flow rate versus CPAPrelationship to better meet the patient's work of breathingrequirements.

Operation of the nCPAP device 22 during periods of time in which thepatient (not shown) exhales (“expiratory phase”) is shown in FIG. 10B.As a point of reference, the flow rate of fluid being delivered to thegenerator body 30 is constant and thus does not change in either of theinspiratory phase or expiratory phase. Thus, pursuant to the previousdiscussion, the first and second secondary jetstreams S₁, S₂ continue tobe produced by the nozzles 50 a, 50 b, respectively, and are directedinto the corresponding passageway 44 a, approaching the axial centerlineC. However, during the expiratory phase, air exhaled by the patiententers the passageway 44 a, flowing in the direction shown by the arrowsE_(p) in FIG. 10B. The exhaled airflow E_(p) essentially simultaneouslyinteracts with, or disrupts, the primary jetstream P (FIG. 10A), as wellas the secondary jetstreams S₁, S₂. Disruption of the secondaryjetstreams S₁, S₂ results in the secondary jetstreams S₁, S₂ no longercombining to form the primary jetstream P. Because the secondaryjetstreams S₁, S₂ are low momentum and collectively provide a largersurface area (as compared to a single, high momentum jetstream), theexhaled air E_(p) readily achieves the desired jetstream disruption. Asshown in FIG. 10B, the disrupted secondary jetstreams S₁, S₂ are causedto split and present minimal resistance to flow of the exhaled airE_(p). Subsequently, the secondary jetstreams S₁, S₂ fold “back” withthe exhaled airflow E_(p). As a result, and as shown in FIG. 10C, theexhaled air E_(p), as well as the “diverted” nozzle airflow N₁, N₂readily flows through the passageway 44 a, through the chamber 58 andthe conduit 60, and is exhausted from the generator body 30 via theexhaust tubing 34. Fluid flow during the expiratory phase is shown byarrows in FIG. 10C.

The disruption in airflow may be characterized by the secondaryjetstreams S₁, S₂ translating into or forming fairly large streamwisevortices (shown schematically in FIG. 10B for the secondary jetstreamsS₁, S₂ at reference “V”). In alternative embodiments alluded to above,formation of streamwise vortices can be further induced bylocating/orienting the nozzles 50 a, 50 b such that the secondaryjetstreams S₁, S₂ impinge upon one another at a point displaced from theaxial centerline C. In any event, the generated vortices V disperse awayfrom the axial centerline C and into the relief zone 220. As a result,the streamwise vortices V prevent (or do not cause) occurrences of flowseparation in the exhaled airflow. The above-described bend (or “flip”)in flow direction from the nozzles 50 a, 50 b may be enhanced due to acoanda effect induced by the relief zone 220 wall. Regardless,resistance to the exhaled air E_(p) by the primary jetstream P and thesecondary jetstreams S₁, S₂ is minimized along the relief zone 220, thuseffectively increasing the hydraulic diameter of the exhaled air E_(p)flow path.

The impinging jetstream and jetstream disruption features of thegenerator body 30 are reflected in the photographs of FIGS. 11A-12B. Inparticular, FIGS. 11A and 12A are longitudinal, cross-sectional views offluid flow within a portion of a fluid circuit established by thegenerator body in accordance with principles of the present invention.By way of reference, the photographs of FIGS. 11A and 12A show a portionof a tube 300 (akin to the tube 42 a or 42 b of FIG. 2A) forming apassageway (akin to the passageway 44 a or 44 b of FIG. 2A) extendingfrom a proximal side 304 to a distal side 306. Further, a pair ofnozzles 308 a, 308 b (akin to the nozzles 50 a, 50 b of FIG. 2A) arefluidly connected to the passageway, and each generate a secondary, lowmomentum jetstream S₁, S₂ (referenced generally) within the tube 300.

With the above in mind, FIG. 11A illustrates the inspiratory phase ofoperation, whereby the secondary jetstreams S₁, S₂ impinge upon oneanother within the tube 300, combining to produce a primary jetstream P.As previously described, the primary jetstream P is directed toward theproximal side 304 (and thus toward the patient (not shown)), and itsmomentum converts to positive pressure. As shown in FIG. 11B thatotherwise provides a transverse cross-sectional photograph of airflowwithin the tube 300 adjacent the nozzles 308 a, 308 b during theinspiratory phase, the secondary jetstreams S₁, S₂ may generate airflowvortices V; however, these vortices V are relatively nominal orinsubstantial, and do not otherwise extend to or interface with an innersurface of the tube 300.

Conversely, during the expiratory phase, and as shown in FIG. 12A,exhaled air from the patient (referenced generally at E_(p)) readilydisrupts the low momentum, secondary jetstreams S₁, S₂. Notably, theprimary jetstream P (FIG. 11A) does not appear in FIG. 12A as thedisruption of the secondary jetstreams S₁, S₂ prevents the secondaryjetstreams S₁, S₂ from combining into the single, coherent primaryjetstream P. FIG. 12B depicts the streamwise vortices V (swirling flow)generated by disruption of the secondary jetstreams S₁, S₂. Thestreamwise vortices V expand or disperse within the tube 300.

Notably, the low momentum jetstream fluid flow created by the nozzles308 is easily disrupted by low momentum/pressure air exhaled from thepatient. Thus, in marked contrast with previous nCPAP devicesincorporating a single jetstream in conjunction with a fluidic fliptechnique during patient exhalation, the nCPAP device, and in particularthe generator body, in accordance with principles of the presentinvention is characterized as requiring a reduced work of breathing bythe patient. This is of great importance for patients with decreasedlung capacity, such as infants or neonates. Further, by combiningmultiple nozzles/jetstreams within a single passageway, an outletdiameter of the nozzles can be reduced, as can overall size of thedevice. Because during normal operation the multiple nozzles are eachgenerating low momentum jetstreams, audible noise produced by the nCPAPdevice of the present invention is reduced as compared to conventionalvariable flow nCPAP generators otherwise relying on a single nozzle,higher momentum jetstream.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present invention.

1. A nasal continuous positive airway pressure (nCPAP) device for usewith an nCPAP system, the device comprising: a generator body defining apatient side and an exhaust side, and forming first and second fluidflow circuits each including: a tube defining: a passageway forming anaxial centerline, a proximal end at which the passageway is open to thepatient side, a distal end at which the passageway is open to theexhaust side; first and second nozzles associated with the tube and eachdefining: an inlet end open to a fluid supply, an outlet end open to thepassageway, wherein each nozzle is adapted to emit a fluid jetstreamfrom the outlet end along a flow direction axis; wherein with respect toeach of the first and second flow circuits, the flow direction axes ofthe corresponding first and second nozzles are non-parallel relative toeach other and relative to the corresponding passageway axialcenterline.
 2. The device of claim 1, wherein the outlet ends of thefirst and second nozzles have an identical diameter.
 3. The device ofclaim 1, wherein the first and second nozzles are transversely alignedrelative to the corresponding passageway axial centerline.
 4. The deviceof claim 1, wherein the first and second nozzles are arranged relativeto the corresponding passageway such that the flow direction axesintersect within the passageway.
 5. The device of claim 4, wherein thefirst and second nozzles are arranged such that the flow direction axesintersect at the axial centerline.
 6. The device of claim 1, wherein thefirst and second nozzles are arranged such that the corresponding flowdirection axes define an included angle in the range of 40-80°.
 7. Thedevice of claim 6, wherein the included angle is approximately 60°. 8.The device of claim 1, wherein the tube defines a distal regionextending from the outlet ends of the nozzles to the distal end, anintermediate region extending from the outlet ends toward the proximalend, and a proximal region extending from the intermediate region to theproximal end, and further wherein the passageway along the intermediateregion immediately adjacent the outlet ends defines an increaseddiameter as compared to a diameter of the passageway at the proximalregion.
 9. The device of claim 1, wherein the first and second fluidcircuits are identical.
 10. The device of claim 1, wherein the tube ofthe first fluid circuit and the tube of the second fluid circuit arejuxtaposed relative to one another.
 11. The device of claim 1, whereinthe inlet ends of first and second nozzles of the first and second fluidcircuits are all fluidly connected to a common manifold.
 12. The deviceof claim 1, wherein each of the tubes further forms a radial slot opento the corresponding passageway adjacent the proximal end thereof, andfurther wherein the generator body forms a pressure monitoring portfluidly connected to the radial slots.
 13. The device of claim 1,wherein the generator body includes a housing within which the tubes areat least partially disposed and forming an opening adjacent the proximalend, respectively, the device further comprising: a patient interfacepiece including: a base forming a pair of lumens each sized for mountingabout the proximal end of a respective one of the tubes; and aninterface portion fluidly connected to the lumens and adapted for fluidconnection to a patient's nares; wherein the housing and the base areconfigured such that upon final assembly, the base nests within theopening.
 14. The device of claim 13, wherein the housing and the baseare configured such that upon final assembly, a pressure monitoringfluid circuit is defined from the lumens to a pressure monitoring portformed in the housing.
 15. The device of claim 13, wherein the interfaceportion is one of a nasal mask and a pair of prongs.
 16. The device ofclaim 1, wherein the generator body further includes: a housing withinwhich the tubes are at least partially disposed, the housing including aside wall terminating at an open face; and first and second flangesextending from opposite sides, respectively, of the side wall, whereinan open-ended gap is defined between each of the flanges and the sidewall, the gap adapted to receive a strap for securing the generator bodyto a patient.
 17. The device of claim 1, wherein the device furtherincludes: a supply tube fluidly connected to the inlet end of each ofthe nozzles for supplying pressurized fluid from a supply source to thenozzles; a pressure monitor tube fluidly connected to the passageways,proximal the nozzle outlet ends, respectively, for sampling fluidpressure within the generator body; an exhaust port defining a conduitfluidly connected to the distal end of each of the tubes, respectively;an exhaust tube attached to the exhaust port and fluidly connected tothe conduit; and a patient interface piece including an interfaceportion, fluidly connected to the passageways and adapted for fluidconnection to a patient's nares.
 18. The device of claim 1, wherein thegenerator body includes: an exhaust port forming an exhaust conduit; ajet body forming each of the nozzles, a distal portion of each of thefirst and second tubes, and a chamber fluidly connected to the distalportions; a manifold cover assembled between the exhaust port and thejet body, the manifold cover forming a supply port; and an interfaceplate forming a proximal portion of each of the first and second tubes,the interface plate being assembled to the jet body such that thecorresponding distal and proximal tube portions are fluidly connected toone another to form the first and second tubes; wherein upon finalassembly, the supply port is fluidly connected to the nozzles and thechamber is fluidly connected to the exhaust conduit.
 19. The device ofclaim 18, wherein the jet body, the interface plate, the manifold cover,and the exhaust port are assembled in a stacked relationship.
 20. Thedevice of claim 1, wherein for at least one of the fluid circuits, atleast one of the nozzles is configured to provide a variable innerdiameter at the outlet end.
 21. A nasal continuous positive airwaypressure (nCPAP) system comprising: a generator body defining a patientside and an exhaust side, and forming first and second fluid flowcircuits each including: a tube forming a passageway defined by aproximal end open to the patient side, a distal end open to the exhaustside, and an axial centerline, first and second nozzles associated withthe tube, each forming a flow path defined by: an inlet end open to afluid supply, an outlet end open to the corresponding passageway,wherein each nozzle is adapted to emit a fluid jetstream from the outletend along a flow direction axis, wherein with respect to each of thefirst and second flow circuits, the flow direction axes of thecorresponding first and second nozzles are non-parallel relative to eachother and relative to the corresponding axial centerline; a fluid supplysource fluidly connected to the inlet end of each of the nozzles,respectively; and exhaust tubing fluidly connected to the distal end ofthe passageways, respectively; wherein upon securement of the generatorbody to a patient's nares, the system is configured to generate acontinuous positive airway pressure in the patient by delivering fluidfrom the fluid supply source to the nozzles that in turn emit secondaryfluid jetstreams that combine to create a primary fluid jetstream withineach of the passageways, the system characterized by an inspiratoryphase of operation in which the primary fluid jetstreams each flowcontinuously toward the patient's nares and an expiratory phase ofoperation in which air exhaled from the patient's nares disrupts thejetstreams such that the exhaled air readily flows though the tubes andto the exhaust tubing.
 22. The system of claim 21, wherein each of thetubes includes an intermediate region extending from the respectivenozzles and a proximal region extending from the intermediate region tothe proximal end, the intermediate region defining an increased innerdiameter as compared to an inner diameter of the proximal region.
 23. Amethod for establishing and delivering a continuous positive airwaypressure to a patient, the method comprising: fluidly connecting agenerator body to nares of the patient, the generator body forming firstand second fluid flow circuits each including a tube defining apassageway having an axial centerline and extending from a proximal endto a distal end, and first and second nozzles associated with the tubeand each defining an inlet end and an outlet end fluidly open to thecorresponding passageway such that the generator body has at least fournozzles, wherein the nozzles are arranged relative to the correspondingtube such that a flow direction axis defined by each of the nozzles arenon-parallel relative to each other and relative to the correspondingaxial centerline; forcing fluid from a supply source to the inlet endsof the nozzles; creating a primary fluid jetstream within each of thepassageways via the respective first and second nozzles emitting asecondary fluid jetstream into the corresponding passageway and towardsthe patient, the secondary fluid jetstream impinging upon each other andcombining to form the primary fluid jetstream; during periods of patientinhalation, the primary fluid jetstreams flowing unencumbered into thepatient's nares; and during periods of patient exhalation, exhaled airfrom the patient acting to disrupt the fluid jetstreams causing areduction in resistance to flow of the exhaled air.
 24. The method ofclaim 23, wherein the secondary fluid jetstreams are characterized asbeing low momentum jets.
 25. The method of claim 23, wherein thesecondary fluid jetstreams associated with a respective one of the fluidcircuits impinge upon each other approximately at the axial centerlineof the corresponding passageway.
 26. The method of claim 23, wherein aflow rate of fluid from the supply source is constant.
 27. The method ofclaim 23, further comprising: monitoring a pressure within the generatorbody by extracting airflow from a port adjacent the nozzles.
 28. Themethod of claim 23, wherein the method is characterized by a singlesupply source providing fluid to all of the nozzles.
 29. The method ofclaim 23, wherein an effective flow path diameter of the passageways isgreater during periods of patient exhalation as compared to periods ofpatient inhalation.
 30. The method of claim 23, wherein the primaryfluid jetstream has a momentum greater than a momentum of the secondaryfluid jetstreams.
 31. The method of claim 23, wherein during periods ofpatient exhalation, the exhaled air causes the secondary jetstreams togenerate streamline vortices.